Since preparing 2021 tax estimated tax vouchers is part of the 2020 tax preparation process (Other Tax Situations), TurboTax Live should be able to provide all the assistance you need.
You can get help from a live agent using TurboTax Live, an online product that lets you get help and guidance from a tax expert when preparing your taxes.
When you use TurboTax Live, you can work with a tax expert whenever you need assistance. You can even talk to a tax expert live while you both look at your return.
See How do I get TurboTax Live? to take the next step.